TESTING/LIN/dtrt06.f(3)

NAME
TESTING/LIN/dtrt06.f

SYNOPSIS

  Functions/Subroutines
subroutine dtrt06 (rcond, rcondc, uplo, diag, n, a, lda, work, rat)
DTRT06

Function/Subroutine Documentation

  subroutine dtrt06 (double precision rcond, double precision rcondc, character uplo, character diag, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) work, double precision rat)

DTRT06

Purpose:

    !>
    !> DTRT06 computes a test ratio comparing RCOND (the reciprocal
    !> condition number of a triangular matrix A) and RCONDC, the estimate
    !> computed by DTRCON.  Information about the triangular matrix A is
    !> used if one estimate is zero and the other is non-zero to decide if
    !> underflow in the estimate is justified.
    !>

Parameters
    RCOND

    !>          RCOND is DOUBLE PRECISION
    !>          The estimate of the reciprocal condition number obtained by
    !>          forming the explicit inverse of the matrix A and computing
    !>          RCOND = 1/( norm(A) * norm(inv(A)) ).
    !>

    RCONDC

    !>          RCONDC is DOUBLE PRECISION
    !>          The estimate of the reciprocal condition number computed by
    !>          DTRCON.
    !>

    UPLO

    !>          UPLO is CHARACTER
    !>          Specifies whether the matrix A is upper or lower triangular.
    !>          = 'U':  Upper triangular
    !>          = 'L':  Lower triangular
    !>

    DIAG

    !>          DIAG is CHARACTER
    !>          Specifies whether or not the matrix A is unit triangular.
    !>          = 'N':  Non-unit triangular
    !>          = 'U':  Unit triangular
    !>

    N

    !>          N is INTEGER
    !>          The order of the matrix A.  N >= 0.
    !>

    A

    !>          A is DOUBLE PRECISION array, dimension (LDA,N)
    !>          The triangular matrix A.  If UPLO = 'U', the leading n by n
    !>          upper triangular part of the array A contains the upper
    !>          triangular matrix, and the strictly lower triangular part of
    !>          A is not referenced.  If UPLO = 'L', the leading n by n lower
    !>          triangular part of the array A contains the lower triangular
    !>          matrix, and the strictly upper triangular part of A is not
    !>          referenced.  If DIAG = 'U', the diagonal elements of A are
    !>          also not referenced and are assumed to be 1.
    !>

    LDA

    !>          LDA is INTEGER
    !>          The leading dimension of the array A.  LDA >= max(1,N).
    !>

    WORK

    !>          WORK is DOUBLE PRECISION array, dimension (N)
    !>

    RAT

    !>          RAT is DOUBLE PRECISION
    !>          The test ratio.  If both RCOND and RCONDC are nonzero,
    !>             RAT = MAX( RCOND, RCONDC )/MIN( RCOND, RCONDC ) - 1.
    !>          If RAT = 0, the two estimates are exactly the same.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 119 of file dtrt06.f.

Author

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